Detection and identification of a serine to arginine sequence variant in a therapeutic monoclonal antibody.

Sequence variants, also known as unintended amino acid substitutions in the protein primary structure, are one of the critical quality attributes needed to be monitored during process development of monoclonal antibodies (mAbs). Here we report on analytical methods for detection and identification of a sequence variant in an IgG1 mAb expressed in Chinese hamster ovary (CHO) cells. The presence of the sequence variant was detected by an imaged capillary isoelectric focusing (ICIEF) assay, showing a new basic species in mAb charge variant profile.

Development of a high throughput protein a well-plate purification method for monoclonal antibodies.

We have developed a new high throughput method for the purification of monoclonal antibodies from harvested cell culture fluid for analytical characterization. This method uses Protein A resin in a 96 well-plate format with protein loading sufficient to perform multiple analyses per well. Resin and buffer conditions were optimized to obtain aggregate and charge variant comparability with three preparative Protein A purified monoclonal antibodies.